A morphological anomaly in Clausocalanus mastigophorus (Claus, 1863) (Copepoda, Calanoida) from St. Peter and St. Paul Archipelago

Copepods are key species in pelagic marine environments. They act as a link between primary producers and fish and also as predators of other major consumers. These organisms are the most abundant and diverse constituents of the marine mesozooplankton and the principal secondary producers in marine food webs, and they can represent up to 80% of the biomass of planktonic metazoans in these environments. Among Copepoda, Calanoida are noteworthy because they are relatively abundant and diverse under certain conditions. The present study reports the first observation of a malformation in a female of C. mastigophorus. The specimen was collected between depths of 40 m and 60 m near the St. Peter and St. Paul archipelago. The authors suggest that this anomaly can be related to parasitic infestation. However, the results of the current study failed to reveal any sign of infestation, either in the anomalous individual or in any other individual of the same genus in the samples.